As most have said here, the JFX200 is a great machine. As far as service goes, ask your dealer two questions. 1. Do you have a Mimaki certified tech who is specifically trained on the JFX on staff? 2. How many units do you have in the field?
If the answer to number 1 is yes, you are in good hands. If they say they don't, you will have to rely on Mimaki which means longer wait time and paying much more for a service call once the machine is out of warranty. The good news is, a properly setup and maintained JFX doesn't require a lot of service calls.
As far as the second answer goes, the more the better. Some smaller dealers might only have 1 or 2 in the field so haven't had a lot of experience servicing them. A tech could go to training and never see the machine again for years until you need a service call. The more machines they have in the field, the more likely they have had to go out on regular service calls.